The invention relates to a storage container for cryogenic compressed gas, particularly a cryo-compressed tank for a motor vehicle, having a storage volume for accommodating the stored gas and an inlet for introducing the gas to be stored into the storage volume.
For operating motor vehicles, for example, ones that use hydrogen or natural gas as a fuel, it is known to store the gas in the subcritical condition in a special pressure resistant container. In this case, the supercold gas is stored in the supercritical condition at a high pressure (13 bar to 350 bar) in a gaseous state. For this purpose, it has to be avoided that heat can enter into the storage container from the environment. The storage container therefore requires a very good, as a rule, double-walled super-insulation with a high vacuum.
When filling or refueling such a storage container with supercold gas, its storage content also has to be kept in a uniform manner at a sufficiently low temperature. This is not always the case at existing storage containers.
According to the invention, a storage container for cryogenic compressed gas, particularly a cryo-compressed tank for a motor vehicle, is created which has a storage volume for the accommodation of the stored gas and an inlet for introducing the gas to be stored into the storage volume, the inlet being designed with a pipe-shaped inlet line projecting into the storage volume, at which inlet line several mutually spaced inlet openings are provided.
The solution according to the invention is based on the recognition that the gas introduced into the storage container has at least a slightly lower temperature than at least portions of the base in the storage volume. In the case of a locally limited charging of gas into the storage volume, the problem therefore occurs that the stored gas is first locally cooled and, only after the refueling, a temperature balancing takes place toward the residual storage volume and its storage device wall. This effect occurs particularly in the case of a partly or completely emptied storage container. The thereby caused later heat input into the stored gas causes a further pressure buildup in the storage container. After the refueling is completed, this leads to a subsequent overshooting of the tank pressure. The storage container is therefore overcharged, which could possibly result in a shortening of the loss-free time of the storage container. Furthermore, non-uniform cooling of the storage container cause strong thermomechanical stresses on its storage container wall which should also be avoided.
By way of the solution according to the invention, the supercold cryo-compressed gas to be stored is axially as well as radially introduced into the storage volume in a particularly uniformly distributed manner. In this case, a purely local cooling, particularly of the storage container wall, is avoided. The solution according to the invention thereby avoids a later overshooting of the tank pressure even in the case of a complete refueling.
In an advantageous further development of the solution according to the invention, the inlet line is designed as a pipe, and the inlet openings are arranged at the pipe on the circumference at an angular distance of 60° (degrees) respectively. Such a design of the inlet line as a pipe, which projects into the storage volume, contributes to an additional temperature equalization of the introduced gas when flowing through the inlet line. With respect to manufacturing, the arranging of the inlet openings in rows can be produced in a safe and cost-effective process.
Preferably, the inlet openings are arranged closely side-by-side in the center of the storage volume. Here, “closely side-by-side” means that the inlet openings are arranged comparatively closely side-by-side at a distance of maximally ten times their own diameter. The selected arrangement in the center of the storage volume contributes to the fact that the introduced gas is uniformly distributed in the storage volume. In addition, this arrangement of the inlet openings results in a largely uniformly far distance between the introduction area and the storage container wall.
Further preferably, the inlet openings extend in an upward direction in the center of the storage volume.
As an alternative, the inlet openings are arranged closely side-by-side on a side of the storage volume. Such an arrangement may be advantageous because the introduced gas can be introduced through the inlet openings in a targeted manner into the storage volume such that it is distributed in the storage volume without coming too close to the storage container wall.
A particularly uniform distribution of the introduced gas into the storage container can be achieved in that the inlet line is designed as a pipe and the inlet openings are arranged at the pipe in three rows spaced at the circumference at an angular distance of 120° respectively.
As an alternative, the inlet line can advantageously be designed as a pipe, at which the inlet openings are arranged in one row. Such a solution can be produced more cost-effectively.
In order to obtain a uniform distribution, particularly in a cylindrical storage volume, it is preferred according to the invention that the pipe extends transversely through the storage volume and the inlet openings are arranged in a spaced manner along the longitudinal dimension of the pipe.
Particularly preferably, 36 circular inlet openings are provided, each with a diameter of 1 mm (millimeter). As an alternative, preferably 12 circular inlet openings are provided, each with a diameter of 1.7 mm.
For a directed introduction of the gas to be introduced, also diagonally to the direction of the used inlet line, the inlet openings are preferably aligned at the pipe diagonally to its longitudinal dimension, particularly at an angle of less than 45°.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.